On Wed, Mar 09, 2011 at 06:45:45PM -0700, Eric Blake wrote:
Currently, the hook function in virFileOperation is extremely limited: it must be async-signal-safe, and cannot modify any memory in the parent process. It is much handier to return a valid fd and operate on it in the parent than to deal with hook restrictions.
* src/util/util.h (VIR_FILE_OP_RETURN_FD): New flag. * src/util/util.c (virFileOperationNoFork, virFileOperation): Honor new flag. --- src/util/util.c | 139 ++++++++++++++++++++++++++++++++++++++++++++++++------ src/util/util.h | 4 +- 2 files changed, 126 insertions(+), 17 deletions(-)
ACK,
+ memset(&msg, 0, sizeof(msg)); + iov.iov_base = &dummy; + iov.iov_len = 1; + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = buf; + msg.msg_controllen = sizeof(buf); + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(sizeof(fd)); + }
....
+ if (flags & VIR_FILE_OP_RETURN_FD) { + VIR_FORCE_CLOSE(pair[1]); + + do { + ret = recvmsg(pair[0], &msg, 0); + } while (ret < 0 && errno == EINTR); + + if (ret < 0) { + ret = -errno; + VIR_FORCE_CLOSE(pair[0]); + while ((waitret = waitpid(pid, NULL, 0) == -1) + && (errno == EINTR)); + goto parenterror; + } + VIR_FORCE_CLOSE(pair[0]); + + /* See if fd was transferred. */ + cmsg = CMSG_FIRSTHDR(&msg); + if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(fd)) && + cmsg->cmsg_level == SOL_SOCKET && + cmsg->cmsg_type == SCM_RIGHTS) { + memcpy(&fd, CMSG_DATA(cmsg), sizeof(fd)); + }
Also might be nice to create two helper methods for this int virFileHandleSendToSocket(int unixfd, int sendfd); int virFileHandleRecvFromSocket(int unixfd); which we can also use in the monitor code that does the same thing Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|